Impact motive implement

ABSTRACT

An impact motive implement for a fluid impact tool or the like. The implement has a main body having an upper cylinder and a lower cylinder. An upper piston and a lower piston are fitted into the two cylinders and connected with a piston rod. An impact tool is disposed under the main body against the upper end of which the lower end of the lower piston strikes when the piston are lowered. A main valve opens and closes an oil inlet port and an oil outlet port leading to the oil chamber in the lower portion within the lower cylinder, and a limiting valve is moved by the upper piston as it rises. The operating portion of the main valve and the limiting valve are correlated so that the main valve will shut off the oil chamber and the oil inlet port and connect the oil chamber and the oil outlet port by feeding compressed high pressure gas in the upper chamber within the upper cylinder to the operating portion of the main valve when the limiting valve is moved by the upper piston, and the oil chamber and the oil inlet port are connected and the oil chamber and the oil outlet are shut off when the limiting valve is not moved by the upper piston, and when the oil chamber is connected with the oil inlet port, the lower piston is pressed upward by the pressure oil fed into the oil chamber.

llnited States Patent [191 Terada IMPACT MOTIVE IMPLEMENT [75] Inventor: 1 Hiromu Terada, Ikoma-gun, Nara,

Japan [73] Assignee: Nippon Pneumatic Manufacturing Co., Ltd., Osaka shi, Japan Filed: Apr. 19 1971 Appl. No.: 13,522

Priinai'y Examinerlames A. Leppink Atl0rney-Wender0th, Lind & Ponack 1 May 29,1973

[5 7] ABSTRACT An impact motive implement for a fluid impact tool or the like. The implement has a main body having an upper cylinder and a lower cylinder. An upper piston and a lower piston are fitted into the two cylinders and connected with a piston rod. An impact tool is disposed under the main body against the upper end of which the lower end of the lower piston strikes when the piston are lowered. A main valve opens and I closes an oil inlet port and an oil outlet port leading to the oil chamber in the lower portion within the lower cylinder, and a limiting valve is moved by the upper piston as it rises. The operating portion of the main valve and the limiting valve are correlated so that the main valve will shut off the oil chamber and the oil inlet port and connect the oil chamber and the oil outlet port by feeding compressed high pressure gas in the upper chamber within the upper cylinder to the operating portion of the main valve when the limiting valve is moved by the upper piston, and the oil chamber and the oil inlet port are connected and the oil chamber and the oil outlet are shut off when the limiting valve is not moved by the upper piston, and when the oil chamber is connected with the oil inlet port, the lower piston is pressed upward by the pressure oil fed into the oil chamber.

3 Claims, 2 Drawing Figures PATENTED HAY 2 9 I975 INVENTOR, HIROMU TE RADA IMPACT MOTIVE IMPLEMENT This invention relates to an impact motive implement actuated by hydraulic pressure and gas pressure of gas such as air, nitrogen and the like.

The conventional impact motive implement compressed air or mechanical driving means. When using compressed air, because air exhausting is performed at every stroke, consumption of compressed air is great, and an air compressor must be kept in operation at all times to supply compressed air. Not only is this inconvenient but it causes noise due to the exhaust sound.

When the drive is a mechanical one, the cam thereof is driven with an electric motor or an air motor, and it has the drawback of being subject to frequent troubles due to vibration and it also causes noise.

The first object of this invention is to provide an impact motive implement which requires no air compressor. The second object of this invention is to provide an I impact motive implement which can be used to obtain a strong impact force by taking advantage of hydraulic pressure and gas pressure. The third object of this invention is to provide an impact motive implement equipped with a rapid liquid exhausting device for exhausting quickly the liquid used to compress gas to obtain a strong impact force with the high pressure gas compressed with hydraulic pressure.

These and further objects are accomplished by the improvement, combination and operation of the parts of the invention,and an embodiment thereof will be illustrated with the accompanying drawing and detailed explanation will be given hereinafter.

' The implement according to the invention is comprised of a main body providedwith an upper cylinder and a lower cylinder, an upper piston fitted into the cylinder atits upper portion and actuated by gas pressure, a lower piston fitted intothe lower cylinder and actuated by hydraulic pressureand a chisel mounted at the lower portion of the main body and movable up-anddown. When the lower piston is raised together with the upper piston by the hydraulic pressure applied to the lower cylinder, the gas within the upper cylinder is compressed, and when each piston reaches the top dead position thereof, then the oil within the lower cylinder is exhausted quickly, the upper and lower pistons are lowered quickly by the pressure of the compressed gas within the upper cylinder, and the lower end of the lower piston strikes against the upper end of the chisel. FIG. 1 is a longitudinal section of an embodiment of the impact motive implement according to this invention, a part of the chisel being broken away.

, FIG. 2 is an elevation of an enlarged longitudinal section of the limiting valve portion of the impact motive implement according to this invention.

This impact motive implement'is comprised of the .main body 11 having an upper cylinder 12 and a lower cylinder 13, an upper piston 14 fitted into the upper cylinder 12, a lower piston 15 fitted into the lower cylinder 13 and a chisel 17 fitted into the chisel holder 16 .at the lower end of the main body and movable up-anddown. The upper piston 14 and the lower piston 15 are connected integrally by a piston rod 18, the upper piston 14 is larger in diameter than the lower piston 15, and the piston rod is smaller in diameter than the lower piston 15. p

In the lower cylinder 13 is slidably fitted a the cylindricalmain valve 19, the lower piston 15 is slidably positioned in said main valve 19, and the lower end portion 20 of the lower piston 15 faces to the upper end of the chisel 17. This lower end portion 20 is smaller in formed integrally the valve piston 24, and this piston is fitted in the middle cylinder 25.

In the inner periphery of the lower cylinder 13 is formed a peripheral groove 26 located at the lower end of and outside of the main valve 19 when said main .valve is in the lowermost position and an oil outlet port 27 communicating with this peripheral groove 26 is formed in the lower cylinder.

' In a part of the periphery of the main valve 19 are formed a plurality of communicating ports 28, a peripheral groove 29 coincident .with said communicating ports when the main valve 19 is in the lowermost position is formed in the inner periphery of the lower cylinder. An oil inlet port 30 communicating with this peripheral groove 29 is formed in the lower cylinder 13. A bushing 31 is fitted securedly inside the lower end of the lower cylinder 13, and the lower end portion 20 of the lower piston 15 is slidable in this bushing 31, and also the lower end of the main valve 19 is fitted around an annular projection 36 on the upper end of the bushing 31. The lower end of the main valve 19, when it is in the lowered position, shuts off said peripheral groove 26 from the oil chamber 22.

Said chisel 17 has a flange 32 formed at the middle thereof, the upper portion of this flange 32 slidably fitting in a bushing 34 fitted securely in a screw threaded cylinder 33 on the lower end of the main body 11. Said chisel holder 16 is threaded on said screw threaded cylinder 33, and the chisel 17 is prevented from dropping off by engagement of the flange 32 with the edge 35 projecting inwardly on the lower end of said chisel holder 16. I

On the upper portion of the main body 11 is secured a handle cap 37, and in a longitudinal hole in the center of this cap 37 is secured a bushing 38. In the middle of this bushing 38 is formed a peripheral groove 39, and in the lower end thereof is concentrically formed a valveport 40 smaller in diameter than theinner diame ter thereof and this valve port 40 communicates with the inside of the upper cylinder 12.

In the wall of the longitudinal hole in the handle cap in which said bushing 38 is positioned is a peripheral groove 41 around the outside of said bushing 38, the peripheral groove 41 and said peripheral groove 39 being connected by a communicating port 42 formed in the bushing 38.

A limiting valve 43 is slidably fitted in said bushing 38 from above for closing said valve port 40. A spring 44 disposed between a spring receiver 45 secured on the cap 37 and a recess 47 inthe limiting valve 43 presses this valve 43 against the valve port 40.

A slender limiting valve stem 46 on the lower end of said limiting valve 40 extends into the upper cylinder 12 through the valve port 40. The limiting valve 43 can thus be lifted from the valve port 40 by pushing said limiting valve stem 46 upwardly by the engagement therewith of the upper end of said piston 14 when said piston 14 is raised. The pressure within the upper cylinder l2 and the recess 47 is kept equal by providing a communicating port 48 extending from the lower end of said limiting valve stem 46 to the recess 47 in the limiting valve.

A longitudinal communicating port 49 is formed in the upper half of the peripheral wall of the main body 11, the upper end thereof is connected to said peripheral groove 41 by a communicating port 50, and the lower end of said communicating port 49 is connected to the opening 51 at the lower end of the middle cylinder 25.

Intermediate the length of said communicating port 49 is an opening 52 opening into the inside of the upper cylinder 12.

Another communicating port 53 is formed in the upper half portion of the wall of the main body 11, and the upper end thereof has an opening 54 opening into the upper cylinder 12, and the lower end thereof has an opening 56 opening into the chamber 55 between the lower cylinder 13 and the middle cylinder 25.

Around the inner periphery of said chamber 55 on the middle cylinder 25 is disposed in the intermediate portion of the upper cylinder 12, and to this opening 57 is connected an air pipe 58. This air pipe 58 is connected to a container for compressed gas such as compressed air or nitrogen and the like. In this air pipe 58 is a check valve 60 and a reducing valve 61 to prevent back current flowing from the opening 57 to the container 59.

To said oil outlet port 27 is connected a pipe leading to an oil tank. An oil pipe connected to the oil inlet port 30 is connected to the exhaust port of a hydraulic pump, and in the oil pipe is provided a suitable control valve which can change-over freely between a state in which a given hydraulic pressure is supplied through the oil inlet port 30 to the oil chamber 22 and a state in which no hydraulic pressure is supplied to the oil chamber 22.

The drawing shows the parts in positions in which hydraulic pressure is not supplied to the oil chamber 22. At this time, gas kept at a given pressure with the reducing valve 61 is supplied to the upper chamber within the upper cylinder 12, and as the pressure is applied to the upper side of the upper piston 14 it presses the upper piston 14 downward, and the piston rod 18, the lower piston 15 and the lower end all integrated with each other are lowered, and the upper end of the chisel 17 is pressed downward by said lower end 20. Thereupon, a part of the gas pressure is directed to the chamber 55 through the opening 54, the communicating port 53 and the opening 56, and acts on the lower side of the upper piston 14. However, because the pressure receiving area of the lower side of said piston 14 is smaller than that of the upper side thereof, the piston is pressed downward.

Further a part of the gas pressure is applied to the lower part of the middle cylinder through the opening 52, the communicating port 49 and the opening 51, and the pressure is applied to the lower side of the valve piston 24 of the main valve 19. However, because the gas pressure in said chamber 55 is applied to the main valve 19 and the upper side of the piston 24 and the pressure receiving area thereof is larger than the lower side thereof, the main valve 19 is moved to the lowermost position.

And, although the gas pressure is applied to the peripheral groove 41, the communicating port 42 and the peripheral groove 39 through said opening 52, the communicating port 49 and the communicating port 50, because the pressure on the upper and lower sides of the limiting valve 43 is kept equal with that in the upper chamber within the upper cylinder 12 by the communicating port 48, the port of said valve 43 is closed by the action of the spring 44.

When hydraulic pressure higher than the gas pressure in the upper chamber within the upper cylinder 12 is supplied to the oil inlet port 30 by operating the controlling valve, the oil enters the oil chamber 22 through the peripheral groove 29 and the communicating port 28 and presses the lower piston 15 upward. The piston rod 18 integral with the lower piston 15 and the upper piston 14 are also moved upward.

When the upper side of the upper piston 14 is raised higher than the openings 52, 54 and 57, the gas in the upper chamber within the upper cylinder 12 is compressed, and the pressure thereof is raised, but because the limiting valve 43 has the bore 48 therethrough, the valve port 40 is kept in the closed state by the spring 44.

When the upper piston is raised further, and the pressure in the upper chamber within the upper cylinder 12 has become fairly high, the upper side of the upper piston 14 presses the limiting valve stem 46 upward and thereby the limiting valve is separated from the valve port 40. Therefore, the gas at high pressure in the upper chamber within the upper cylinder 12, flows through the valve port 40, the peripheral groove 39, the communicating port 50, the communicating port 49 and the opening 51 and presses the bottom of the piston 24 of the main valve 19 upwardly.

Thereupon, because the gas pressure in the chamber 55 and the upper chamber within the middle cylinder 25 communicating therewith is reduced, said piston 24 and the main valve 19 are raised rapidly, and when the lower end of the main valve 19 is drawn off of the annular projection 36 on said bushing 31, the oil chamber 22 is placed in communication with the peripheral groove, and also the communicating port 28 of the main valve 19 is moved above the peripheral groove 29 and shuts off the oil chamber 22 from the oil inlet port 30.

Therefore, upward hydraulic pressure on the lower piston 15 disappears and the upper piston 14, the piston rod 18, the lower piston 15 and the like are lowered rapidly by the high gas pressure applied to the upper side of the upper piston 14, and the lower end 20 strikes against the upper end of the chisel 17.

The oil in the oil chamber 22 is forced out of chamber 22 during the lowering of the lower piston 15 and is returned to the oil tank through the peripheral groove 26 and the oil outlet port 27. When the upper side of the upper piston 14 is lowered below openings 52, 54, 57, the pressure in the upper chamber within the upper cylinder 12 is returned to its constant pressure and the limiting valve is returned to its original state and the valve port 40 is closed, and as the gas pressure in the lower portion within said middle cylinder 25 is returned to its original valve, the main value 19 is also lowered and the lower end thereof is fitted over said annular projection 36 and cuts off the oil chamber 22 from the peripheral groove 26, and the port 28 of the main valve 119 is brought into coincidence with the peripheral groove 29.

Accordingly, during the state wherein oil at a given pressure is fed to the oil inlet 30 upon the opening of the control valve in the oil pipe connected to the oil inlet port 30, the operation described above is repeated and the upper piston 14, the piston rod 18, the lower piston and the like are moved up and down, and the lower end strikes against the upper end of the chisel l7 repeatedly so that the chisel 1 7 may be made to accomplish desirable work.

During said operation, the gas reciprocates only between the upper and lower portions of the upper cylinder 12, within the middle cylinder and the chamber 55, and no air is exhausted. This differs from conventional impact motive implements. Consequently, there is no noise at all due to the air exhausting sound. Moreover, there is little consumption of gas, and because it is sufficient to supply enough only to compensate for slight leakage during operation, only a gas container of a small capacity is required for keeping a constant gas pressure and there is no need for a compressor.

The impact motive implement according to this invention, however, requires a hydraulic pump, but as most machines for civil engineering have hydraulic pumps, hydraulic pressure may be easily by connecting to these hydraulic pumps.

- It is necessary to reduce the resistance due to oil as much as possible by exhausting the oil in the oil chamber 22 rapidly for lowering quickly the upper piston 14 and the like. Therefore, the peripheral groove 26, the

oil outlet port 27 and thepipe connecting the oil outlet port 27 with the oil tank should be made larger and also the main valve 19 should be raised quickly by the action of the high pressure gas so that the entire lower periphery of the oil chamber is to be communicated instantaneously'with the peripheral groove 26, but when the oil exhausting speed is too high, cavitation may be caused and-the portion contacting the to oil might be damaged and then the pressure in the oil chamber at the time of exhausting will be increased.

In this invention, however, the main valve 19 is cylindrical and when the main valve 19 is raised, due to the presence of said peripheral groove 26, the oil chamber 22 is communication with the peripheral groove 26 and the oil in the oil chamber 22 flows into the peripheral groove 26, with a speed which is considerably reduced,

. and chapping on the inner surface of the oil outlet port 27 due to cavitation during exhausting can be prevented.

Also, because the speed of the oil is reduced, an increase in the pressure of the oil being exhausted due to the resistance of the pipe passage can be prevented, and there is no fear of an obstacle, as the oil is being exhausted, to the lowering of the upper piston 14 and the lower piston 15.

Moreover, in theembodiment described, the mechanism of the main valve 19 is shown as being disposed in the main body 11,,but the mechanism of the main valve 19 can be disposed in an intermediate portion of the exhausting pipe to the oil chamber by forming it separately from the main body.

What is claimed is:

1. An impact motive implement, comprising a main body having an upper cylinder and a lower cylinder, an

upper piston and a lower piston titted in the respective cylinders and a piston rod connecting said pistons and a lower end on said lower piston having a smaller diameter than said lower cylinder, a tool holder on the lower end of the main body and an impact tool movably mounted in said tool holder and against the upper end of which the lower end of the lower piston strikes when both pistons are lowered, said body having an' oil inlet port opening into said lower cylinder at a point below said lower piston when said lower piston is in the lowermost position and said body having an oil outlet port opening out of said lower cylinder, a compressed gas operated main valve slidable in said implement be tween a first position in which it closes the oil outlet port and opens said oil inlet port and a second position in which it closes said oil inlet port and opens said oil outlet port, said main body having a passage therethrough from said upper cylinder to said main valve, and a limiting valve in said passage and normally closing said passage and engageable by said upper piston near the upper limit of its movement for opening said limiting valve, whereby when the main valve is in the position with the oil inlet port open, oil under pressure can be admitted to the lower cylinder to raise the pistons, compressing gas in the upper cylinder above the upper piston, until the upper piston opens the limiting valve, whereupon the compressed gas in the upper cylinder shifts the main valve to open the oil outlet port and the compressed gas in the upper cylinder drives the pistons downwardly against the impact tool.

2. An impact motive implement as claimed in claim 1 in which said main body has a middle cylinder between said upper and lower cylinders through which said piston rod extends, said main valve being a cylindrical sleeve slidable in said lower cylinder between the wall of said cylinder and said lower piston, the'oil outlet port being in the bottom of said lower piston and being opened when said main valve is raised above the lowermost position thereof, and said main valve having an opening therein which in the lowermost position of the main valve is aligned with said oil inlet port, and the upper end of said main valve having a piston portion slidable in said middle cylinder, said passage through the main body opening into said middle cylinder beneath the main valve piston.

3. An impact motive implement as claimed in claim 2 wherein said main body has a further passage therethrough from a point in said upper cylinder just above said upper piston when said upper piston is in the lowermost position to the middle cylinder above the uppermost position of the main valve piston, whereby when the pistons have reached their lowermost position, gas under pressure will flow into said middle cylinder and return said main valve to the lowermost position.

t t t t 4 

1. An impact motive implement, comprising a main body having an upper cylinder and a lower cylinder, an upper piston and a lower piston fitted in the respective cylinders and a piston rod connecting said pistons and a lower end on said lower piston having a smaller diameter than said lower cylinder, a tool holder on the lower end of the main body and an impact tool movably mounted in said tool holder and against the upper end of which the lower end of the lower piston strikes when both pistons are lowered, said body having an oil inlet port opening into said lower cylinder at a point below said lower piston when said lower piston is in the lowermost position and said body having an oil outlet port opening out of said lower cylinder, a compressed gas operated main valve slidable in said implement between a first position in which it closes the oil outlet port and opens said oil inlet port and a second position in which it closes said oil inlet port and opens said oil outlet port, said main body having a passage therethrough from said upper cylinder to said main valve, and a limiting valve in said passage and normally closing said passage and engageable by said upper piston near the upper limit of its movement for opening said limiting valve, whereby when the main valve is in the positioN with the oil inlet port open, oil under pressure can be admitted to the lower cylinder to raise the pistons, compressing gas in the upper cylinder above the upper piston, until the upper piston opens the limiting valve, whereupon the compressed gas in the upper cylinder shifts the main valve to open the oil outlet port and the compressed gas in the upper cylinder drives the pistons downwardly against the impact tool.
 2. An impact motive implement as claimed in claim 1 in which said main body has a middle cylinder between said upper and lower cylinders through which said piston rod extends, said main valve being a cylindrical sleeve slidable in said lower cylinder between the wall of said cylinder and said lower piston, the oil outlet port being in the bottom of said lower piston and being opened when said main valve is raised above the lowermost position thereof, and said main valve having an opening therein which in the lowermost position of the main valve is aligned with said oil inlet port, and the upper end of said main valve having a piston portion slidable in said middle cylinder, said passage through the main body opening into said middle cylinder beneath the main valve piston.
 3. An impact motive implement as claimed in claim 2 wherein said main body has a further passage therethrough from a point in said upper cylinder just above said upper piston when said upper piston is in the lowermost position to the middle cylinder above the uppermost position of the main valve piston, whereby when the pistons have reached their lowermost position, gas under pressure will flow into said middle cylinder and return said main valve to the lowermost position. 